ClickHouse/dbms/src/Storages/MergeTree/MergeTreeDataPart.h
2018-03-14 19:00:02 +03:00

330 lines
13 KiB
C++

#pragma once
#include <Core/Row.h>
#include <Core/Block.h>
#include <Core/NamesAndTypes.h>
#include <Storages/MergeTree/MergeTreePartInfo.h>
#include <Storages/MergeTree/MergeTreePartition.h>
#include <Columns/IColumn.h>
#include <shared_mutex>
class SipHash;
namespace DB
{
/// Checksum of one file.
struct MergeTreeDataPartChecksum
{
using uint128 = CityHash_v1_0_2::uint128;
UInt64 file_size {};
uint128 file_hash {};
bool is_compressed = false;
UInt64 uncompressed_size {};
uint128 uncompressed_hash {};
MergeTreeDataPartChecksum() {}
MergeTreeDataPartChecksum(UInt64 file_size_, uint128 file_hash_) : file_size(file_size_), file_hash(file_hash_) {}
MergeTreeDataPartChecksum(UInt64 file_size_, uint128 file_hash_, UInt64 uncompressed_size_, uint128 uncompressed_hash_)
: file_size(file_size_), file_hash(file_hash_), is_compressed(true),
uncompressed_size(uncompressed_size_), uncompressed_hash(uncompressed_hash_) {}
void checkEqual(const MergeTreeDataPartChecksum & rhs, bool have_uncompressed, const String & name) const;
void checkSize(const String & path) const;
};
/** Checksums of all non-temporary files.
* For compressed files, the check sum and the size of the decompressed data are stored to not depend on the compression method.
*/
struct MergeTreeDataPartChecksums
{
using Checksum = MergeTreeDataPartChecksum;
/// The order is important.
using FileChecksums = std::map<String, Checksum>;
FileChecksums files;
void addFile(const String & file_name, UInt64 file_size, Checksum::uint128 file_hash);
void add(MergeTreeDataPartChecksums && rhs_checksums);
/// Checks that the set of columns and their checksums are the same. If not, throws an exception.
/// If have_uncompressed, for compressed files it compares the checksums of the decompressed data. Otherwise, it compares only the checksums of the files.
void checkEqual(const MergeTreeDataPartChecksums & rhs, bool have_uncompressed) const;
/// Checks that the directory contains all the needed files of the correct size. Does not check the checksum.
void checkSizes(const String & path) const;
/// Serializes and deserializes in human readable form.
bool read(ReadBuffer & in); /// Returns false if the checksum is too old.
bool read_v2(ReadBuffer & in);
bool read_v3(ReadBuffer & in);
bool read_v4(ReadBuffer & in);
void write(WriteBuffer & out) const;
bool empty() const
{
return files.empty();
}
/// Checksum from the set of checksums of .bin files.
void summaryDataChecksum(SipHash & hash) const;
String toString() const;
static MergeTreeDataPartChecksums parse(const String & s);
};
class MergeTreeData;
/// Description of the data part.
struct MergeTreeDataPart
{
using Checksums = MergeTreeDataPartChecksums;
using Checksum = MergeTreeDataPartChecksums::Checksum;
MergeTreeDataPart(MergeTreeData & storage_, const String & name_, const MergeTreePartInfo & info_)
: storage(storage_), name(name_), info(info_)
{
}
MergeTreeDataPart(MergeTreeData & storage_, const String & name_);
const Checksum * tryGetChecksum(const String & name, const String & ext) const;
/// Returns checksum of column's binary file.
const Checksum * tryGetBinChecksum(const String & name) const;
/// Returns checksum of column's mrk file.
const Checksum * tryGetMrkChecksum(const String & name) const;
/// Returns the size of .bin file for column `name` if found, zero otherwise
UInt64 getColumnCompressedSize(const String & name) const;
UInt64 getColumnUncompressedSize(const String & name) const;
/// Returns the size of .mrk file for column `name` if found, zero otherwise
UInt64 getColumnMrkSize(const String & name) const;
/// Returns the name of a column with minimum compressed size (as returned by getColumnSize()).
/// If no checksums are present returns the name of the first physically existing column.
String getColumnNameWithMinumumCompressedSize() const;
/// Returns full path to part dir
String getFullPath() const;
/// Returns part->name with prefixes like 'tmp_<name>'
String getNameWithPrefix() const;
bool contains(const MergeTreeDataPart & other) const { return info.contains(other.info); }
/// If the partition key includes date column (a common case), these functions will return min and max values for this column.
DayNum_t getMinDate() const;
DayNum_t getMaxDate() const;
MergeTreeData & storage;
String name;
MergeTreePartInfo info;
/// A directory path (relative to storage's path) where part data is actually stored
/// Examples: 'detached/tmp_fetch_<name>', 'tmp_<name>', '<name>'
mutable String relative_path;
size_t rows_count = 0;
size_t marks_count = 0;
std::atomic<UInt64> size_in_bytes {0}; /// size in bytes, 0 - if not counted;
/// is used from several threads without locks (it is changed with ALTER).
time_t modification_time = 0;
/// When the part is removed from the working set. Changes once.
/// Use DATE_LUT_MAX which is almost 2^32 to produce correct time_t to String conversions using DateLUT
mutable std::atomic<time_t> remove_time { DATE_LUT_MAX };
/// If true, the destructor will delete the directory with the part.
bool is_temp = false;
/// If true it means that there are no ZooKeeper node for this part, so it should be deleted only from filesystem
bool is_duplicate = false;
/**
* Part state is a stage of its lifetime. States are ordered and state of a part could be increased only.
* Part state should be modified under data_parts mutex.
*
* Possible state transitions:
* Temporary -> Precommitted: we are trying to commit a fetched, inserted or merged part to active set
* Precommitted -> Outdated: we could not to add a part to active set and doing a rollback (for example it is duplicated part)
* Precommitted -> Commited: we successfully committed a part to active dataset
* Precommitted -> Outdated: a part was replaced by a covering part or DROP PARTITION
* Outdated -> Deleting: a cleaner selected this part for deletion
* Deleting -> Outdated: if an ZooKeeper error occurred during the deletion, we will retry deletion
*/
enum class State
{
Temporary, /// the part is generating now, it is not in data_parts list
PreCommitted, /// the part is in data_parts, but not used for SELECTs
Committed, /// active data part, used by current and upcoming SELECTs
Outdated, /// not active data part, but could be used by only current SELECTs, could be deleted after SELECTs finishes
Deleting /// not active data part with identity refcounter, it is deleting right now by a cleaner
};
/// Current state of the part. If the part is in working set already, it should be accessed via data_parts mutex
mutable State state{State::Temporary};
/// Returns name of state
static String stateToString(State state);
String stateString() const;
String getNameWithState() const
{
return name + " (state " + stateString() + ")";
}
/// Returns true if state of part is one of affordable_states
bool checkState(const std::initializer_list<State> & affordable_states) const
{
for (auto affordable_state : affordable_states)
{
if (state == affordable_state)
return true;
}
return false;
}
/// Throws an exception if state of the part is not in affordable_states
void assertState(const std::initializer_list<State> & affordable_states) const;
/// In comparison with lambdas, it is move assignable and could has several overloaded operator()
struct StatesFilter
{
std::initializer_list<State> affordable_states;
StatesFilter(const std::initializer_list<State> & affordable_states) : affordable_states(affordable_states) {}
bool operator() (const std::shared_ptr<const MergeTreeDataPart> & part) const
{
return part->checkState(affordable_states);
}
};
/// Returns a lambda that returns true only for part with states from specified list
static inline StatesFilter getStatesFilter(const std::initializer_list<State> & affordable_states)
{
return StatesFilter(affordable_states);
}
/// Primary key (correspond to primary.idx file).
/// Always loaded in RAM. Contains each index_granularity-th value of primary key tuple.
/// Note that marks (also correspond to primary key) is not always in RAM, but cached. See MarkCache.h.
using Index = Columns;
Index index;
MergeTreePartition partition;
/// Index that for each part stores min and max values of a set of columns. This allows quickly excluding
/// parts based on conditions on these columns imposed by a query.
/// Currently this index is built using only columns required by partition expression, but in principle it
/// can be built using any set of columns.
struct MinMaxIndex
{
Row min_values;
Row max_values;
bool initialized = false;
public:
MinMaxIndex() = default;
/// For month-based partitioning.
MinMaxIndex(DayNum_t min_date, DayNum_t max_date)
: min_values(1, static_cast<UInt64>(min_date))
, max_values(1, static_cast<UInt64>(max_date))
, initialized(true)
{
}
void load(const MergeTreeData & storage, const String & part_path);
void store(const MergeTreeData & storage, const String & part_path, Checksums & checksums) const;
void update(const Block & block, const Names & column_names);
void merge(const MinMaxIndex & other);
};
MinMaxIndex minmax_idx;
Checksums checksums;
/// Columns description.
NamesAndTypesList columns;
using ColumnToSize = std::map<std::string, UInt64>;
/** It is blocked for writing when changing columns, checksums or any part files.
* Locked to read when reading columns, checksums or any part files.
*/
mutable std::shared_mutex columns_lock;
/** It is taken for the whole time ALTER a part: from the beginning of the recording of the temporary files to their renaming to permanent.
* It is taken with unlocked `columns_lock`.
*
* NOTE: "You can" do without this mutex if you could turn ReadRWLock into WriteRWLock without removing the lock.
* This transformation is impossible, because it would create a deadlock, if you do it from two threads at once.
* Taking this mutex means that we want to lock columns_lock on read with intention then, not
* unblocking, block it for writing.
*/
mutable std::mutex alter_mutex;
~MergeTreeDataPart();
/// Calculate the total size of the entire directory with all the files
static UInt64 calculateTotalSize(const String & from);
void remove() const;
/// Makes checks and move part to new directory
/// Changes only relative_dir_name, you need to update other metadata (name, is_temp) explicitly
void renameTo(const String & new_relative_path, bool remove_new_dir_if_exists = true) const;
/// Renames a part by appending a prefix to the name. To_detached - also moved to the detached directory.
void renameAddPrefix(bool to_detached, const String & prefix) const;
/// Populates columns_to_size map (compressed size).
void accumulateColumnSizes(ColumnToSize & column_to_size) const;
/// Initialize columns (from columns.txt if exists, or create from column files if not).
/// Load checksums from checksums.txt if exists. Load index if required.
void loadColumnsChecksumsIndexes(bool require_columns_checksums, bool check_consistency);
/// Checks that .bin and .mrk files exist
bool hasColumnFiles(const String & column) const;
/// For data in RAM ('index')
UInt64 getIndexSizeInBytes() const;
UInt64 getIndexSizeInAllocatedBytes() const;
/// Total size of *.mrk files
UInt64 getTotalMrkSizeInBytes() const;
private:
/// Reads columns names and types from columns.txt
void loadColumns(bool require);
/// If checksums.txt exists, reads files' checksums (and sizes) from it
void loadChecksums(bool require);
/// Loads index file. Also calculates this->marks_count if marks_count = 0
void loadIndex();
/// Load rows count for this part from disk (for the newer storage format version).
/// For the older format version calculates rows count from the size of a column with a fixed size.
void loadRowsCount();
void loadPartitionAndMinMaxIndex();
void checkConsistency(bool require_part_metadata);
};
using MergeTreeDataPartState = MergeTreeDataPart::State;
}